矩形类

Question

大家好，我对 c++ 很陌生，可能对我试图解决的这个问题感到头疼。我所要求的只是对我的错误的一个很好的视觉解释和解决方案，甚至更好的是修改后的源代码。感谢所有对我的问题感兴趣的人。

问题出在： 设计一个名为 rectangle 的类来表示一个矩形。该类必须包含：

• 两个名为 width 和 height 的双精度数据字段用于指定矩形的宽度和高度。
• 一个无参数构造函数，创建一个宽度为 1 高度为 1 的默认矩形。
• 创建具有指定宽度和高度的矩形的构造函数
• 所有数据字段的访问器和修改器函数
• 名为 get Area() 的函数返回此矩形的面积
• 一个名为 getPerimeter() 的函数，它返回 peremter。

为该类绘制 UML 图。实现类。编写一个创建两个矩形对象的测试程序。将宽度 4 和高度 40 分配给第一个对象，将宽度 3.5 和高度 35.9 分配给第二个对象。显示两个对象的属性并找出它们的面积和周长。

这是我目前所拥有的：

#include <iostream>
using namespace std;

class Rectangle
{    
public:      
  double height;

public:
  double width;
  Rectangle()
  {
      width = 4;        
  }

  rectangle(double newArea)

  double height;
  height()
  (
      height = 40
      {
          {
          area = height* width;
          }


  double getArea()
  {
    return Area;
  }

  bool isOn()
  {
    return on;
  }


  double getPerimeter()
  {
    return Perimeter;
  }

  void setPerimeter(double radius)

  cout << "The area of the  Rectangle" 
 << rectangle1.area<<"is"<<rectangle1.getArea()<< endl;
 cout<<"The area of  the Rectangle"
 <<rectangle.area2.area<<"is"<<rectangle2.getArea()<<endl; 


  return 0;
}

Answer 1

如果您想了解这里发生了什么，请查看这里

#include <iostream> 
using namespace std; 

class Rectangle{ 
private:        // In nearly all cases you want to keep your member variables private
  double height;    // This allows you to be certain of how they are accessed. 
  double width;     // This provides a level of security to the class.

public:         // Only need one public:
  // Constructors are called when you define a new variable of type Rectangle
  Rectangle()       // No arguments means this constructor takes no extra input when called.
  { 
    width = 1.0;        // Sets width and height to 1
    height = 1.0;
  } 
  Rectangle(double a_width, double a_height) {  // Constructor needs exact(case-sensitive) match of class-name
    /* Set width and hieght to the arguments passed into the constructor in here.*/         
  } 
  // Accessor / Mutator methods are more easily called get/set methods.
  double getHeight(){   // Get height called on rectangle class
    return height;      // Returns the value of the class member "height"
  }

  /*Make a method to get the width here.*/

  // In c++ you can return the results of equations directly
  // i.e. 
  // int x = 2;
  // return x*x;  // returns 4
  // Try something simliar for getArea() and getPerimeter();

  double getArea() const 
  { 
      return /*area equation goes here*/ ;
  } 
  double getPerimeter() const
  {                     
    return /*perimeter equation goes here*/; 
  } 
}
  // You should split these displaying statements into the main function,
  // Which is what you meant to do, right? ;)
  int main(){
    // In order to use your new class, you need to declare a variable of its type
      Rectangle rectangle1;     
      // When you declare a new variable without any arguments its default constructor is called.
      // This means that the rectangle class decides to use the height = 1; width = 1; constructor from above.
      // You can check this using your getHeight() and getWidth(), when you implement them.

      cout << "The area of the Rectangle is" << rectangle1.getArea() << endl; 

  return 0; 
} 

啊，让我想起了TAing CSCI1100

Answer 2

这是一个可行的解决方案，

源代码：

#include <iostream>

using namespace std;

class Rectangle {
    private:
        double width;
        double height;
    public:
        Rectangle(double w=1, double h=1);

        double getWidth();
        void setWidth(double w);

        double getHeight();
        void setHeight(double h);

        double getArea();
        double getPerimeter();
};

Rectangle::Rectangle(double w, double h):width(w),height(h) {}

double Rectangle::getWidth() { return width; }

void Rectangle::setWidth(double w) {width = w; }

double Rectangle::getHeight() { return height; }

void Rectangle::setHeight(double h) { height = h; }

double Rectangle::getArea() { return width*height; }

double Rectangle::getPerimeter() { return 2*(width+height); }

int main()
{
    Rectangle r1(4,40);
    Rectangle r2(3.5,35.9);

    cout << "Rectangle #1 :: width[" << r1.getWidth() << "] height[" << r1.getHeight() << "] area[" << r1.getArea() << "] perimeter[" << r1.getPerimeter() << "]" << endl;
    cout << "Rectangle #2 :: width[" << r2.getWidth() << "] height[" << r2.getHeight() << "] area[" << r2.getArea() << "] perimeter[" << r2.getPerimeter() << "]" << endl;
}

输出：

Rectangle #1 :: width[4] height[40] area[160] perimeter[88]
Rectangle #2 :: width[3.5] height[35.9] area[125.65] perimeter[78.8]

Answer 3

第 1 步：删除所有不在规范中的代码：

class Rectangle {

private:
    double height;
    double width;

public:
    Rectangle() {
        // fill in code here
    }

    Rectangle(double width, double height) {
        // fill in code here
    }

    double getArea() {
        // fill in code here
    }

    double getPerimeter() {
         // fill in code here
    }

    double getWidth() {
        // fill in code here
    }

    void setWidth(double newWidth) {
        // fill in code here
    }

    double getHeight() {
        // fill in code here
    }

    void setHeight(double newHeight) {
        // fill in code here
    }

};

您的其余代码只是让这变得更加复杂。您不需要面积或周长变量，并且接受面积作为参数的构造函数没有意义（您似乎将矩形视为圆形）。